Introduction
Your Antminer’s firmware is the software brain running on its control board — the operating system that orchestrates ASIC chip communication, pool connections, temperature management, fan control, and hashrate optimization. Like any software, firmware evolves. Bitmain releases updates that patch security vulnerabilities, fix bugs, improve stability, and occasionally unlock performance gains. And beyond Bitmain’s stock firmware, a thriving ecosystem of alternative firmware projects — Braiins OS+, VNish, LuxOS — pushes these machines far beyond their factory capabilities with autotuning, underclocking, overclocking, and power management features that stock firmware simply does not offer.
Updating firmware is one of the most impactful things you can do for your mining operation. A single firmware update can improve efficiency by 5-25%, patch a vulnerability that could expose your miner to remote exploits, add support for new pool protocols like Stratum V2, or recover a machine that has been behaving erratically since its last power outage. And yet, firmware updates are also one of the areas where miners make the most costly mistakes — flashing the wrong firmware for their control board type, interrupting a flash mid-write, or skipping the backup step that would have saved them hours of recovery work.
This guide covers every Antminer generation from the legendary S9 through the current S21 series. It covers stock Bitmain firmware, all three major alternative firmware platforms, every update method (web interface, SD card, USB, SSH, and dedicated toolboxes), and the troubleshooting procedures for when things go wrong. Whether you are running a single S9 as a Bitcoin Space Heater in your basement or managing a fleet of S21s in a facility, this guide gives you the knowledge to handle firmware with confidence.
D-Central Technologies has been flashing, recovering, and customizing Antminer firmware since 2016. We have performed firmware operations on 2,500+ miners at our repair facility in Laval, Quebec — from SD card recoveries on bricked S17s to mass Braiins OS+ deployments on S19 fleets. We maintain a comprehensive Firmware Download Center with stock and legacy firmware files for every Antminer model. If anything in this guide exceeds your comfort level, our repair team handles firmware issues daily: 1-855-753-9997.
Difficulty: Intermediate — Requires basic familiarity with your miner’s web interface and network configuration. SD card and SSH methods require moderate technical comfort.
Time Required: 15–30 minutes for a standard web interface update. SD card and alternative firmware installations may take 30–60 minutes including preparation and verification.
Understanding Antminer Firmware
Before you flash anything, you need to understand what you are flashing and what your options are. Antminer firmware is not a single universal package — it varies by model generation, control board type, and whether you want to stay with Bitmain’s stock software or switch to an alternative platform that unlocks capabilities Bitmain intentionally restricts.
Stock Bitmain Firmware
Stock firmware is what ships on your miner from the factory. It is developed by Bitmain, tested against their specific hardware configurations, and designed for stability above all else. Stock firmware gives you basic pool configuration, temperature monitoring, fan speed control, and a web dashboard for management. What it does not give you: per-chip autotuning, underclocking for efficiency, overclocking for maximum hashrate, advanced power management, Stratum V2 support, or granular control over your hardware.
Bitmain releases firmware updates through their official support site. Updates are model-specific and often control-board-specific — you cannot flash S19 firmware onto an S21, and you cannot flash Xilinx firmware onto an Amlogic control board. Getting this wrong can brick your miner.
Alternative Firmware Options
Alternative firmware replaces Bitmain’s stock software entirely, giving you capabilities that transform a consumer appliance into a precision-tuned mining instrument. Three platforms dominate the Antminer alternative firmware space:
Firmware Comparison: Stock vs. Braiins OS+ vs. VNish vs. LuxOS
| Feature | Stock (Bitmain) | Braiins OS+ | VNish | LuxOS |
|---|---|---|---|---|
| Autotuning | No | Per-chip autotuning | Yes (profiles) | Yes (dynamic) |
| Underclocking | No | Yes — set power target in watts | Yes — preset profiles | Yes — watt-level control |
| Overclocking | No | Yes — up to hardware limit | Yes — up to +30% | Yes — controlled OC |
| Stratum V2 | No | Yes — native support | No | No |
| 120V Support (PSU Bypass) | No | No | No | Yes — S19 series |
| Immersion Cooling Profiles | Limited | Yes | Yes | Yes |
| Remote Management | Web UI only | BOS Toolbox + Farm Monitor | Hashcore Toolkit | LuxOS Commander |
| Dev Fee | None | ~2% (depends on pool) | 2.8% | Varies by plan |
| SOC 2 Certified | No | No | No | Yes — Type 2 |
| Revert to Stock | N/A | Yes — built-in tool | Yes — SD card | Yes — remove SD card |
| Model Support | All Antminer models | S9, S17 series, S19 series, S21 series | S9, S17 series, S19 series, S21 series, L7, L9 | S19 series, S21 series |
| Installation Method | Web UI / SD card | BOS Toolbox (SSH) / SD card | Hashcore Toolkit / SD card / Web UI | LuxOS Commander / SD card |
Braiins OS+ is the gold standard for efficiency-focused miners. Its per-chip autotuning analyzes every individual ASIC chip on every hashboard and adjusts frequencies so that higher-quality chips work harder while lower-quality chips run at reduced speeds. The result is dramatically better joules-per-terahash efficiency at any given power target. Braiins OS+ is also the only firmware with native Stratum V2 support — a next-generation mining protocol that adds authenticated encryption and allows miners to select their own transactions, a massive win for decentralization. For bitcoiners who care about sovereignty and efficiency, Braiins is the obvious choice.
VNish is the power user’s firmware. Developed by the largest independent mining software team, VNish offers aggressive overclocking profiles, preset-based tuning, chip throttling for the S21 series, and a simple 2.8% DevFee model with no subscriptions and free updates. VNish supports the widest range of Antminer models including Scrypt miners (L7, L9), making it the go-to choice for multi-algorithm operations. Its Hashcore Toolkit enables remote installation and management at scale.
LuxOS is the enterprise-grade option. Developed by Luxor Technologies (a US-based company), LuxOS is the first and only ASIC firmware with SOC 2 Type 2 certification — meaning it has been independently audited for security, availability, and data integrity. LuxOS features dynamic hashprice-responsive tuning: it automatically shifts to ultra-efficient mode when hashprice drops and enables overclocking when conditions improve. Its standout feature for home miners is PSU Bypass Mode, which allows certain S19 models to run on standard 120V household power — eliminating the biggest barrier to running industrial-grade ASICs at home.
Know Your Control Board
This is where most firmware mistakes happen. Antminer S19 and S21 series miners ship with different control board types, and each type requires different firmware. Flashing the wrong firmware for your control board type can brick the device. Here is how to identify what you have:
Control Board Types by Generation
| Control Board | SoC | Found In | SD Card Slot | Key Identifier |
|---|---|---|---|---|
| Xilinx (Zynq) | Xilinx Zynq SoC | Early S19 (C55/C71 boards) | External — next to Ethernet port | FPGA component handles chip data streaming |
| BeagleBone Black (BBB) | TI AM335x | S19 (late 2021+), some S19j Pro | Internal — must open enclosure | SD slot on underside of board, inside miner |
| Amlogic | Amlogic A311D | Late S19, S21, T21 (2023+) | None — Micro USB port instead | Micro USB port on front of control board |
| CV1835 (Cvitek) | Cvitek CV1835 | Some S19 XP, newer batches | Varies | Check control board markings |
Starting in March 2024, Bitmain began shipping Amlogic control boards with firmware locks that prevent installation of third-party firmware. If your S19 or S21 has an Amlogic board manufactured after this date, you will need an unlocking procedure before installing Braiins OS+, VNish, or LuxOS. This typically involves a specialized unlocking kit or service. D-Central can unlock Amlogic boards — contact our repair team for details.
For older generations, identification is simpler. The S9 uses a single control board type with an external MicroSD slot. The S17/T17 series uses a Xilinx-based control board with an external SD card slot accessible from outside the miner. When in doubt, check the D-Central Control Board Guide for detailed identification instructions with photos.
Before You Update
Every firmware update carries risk. The flash process rewrites the control board’s storage — if it is interrupted, corrupted, or done with the wrong file, you can end up with a miner that will not boot. Fifteen minutes of preparation can save you hours of recovery work. Follow this checklist before you touch any firmware file.
1. Back Up Your Current Configuration
Before you flash anything, record your miner’s current state. If the update goes wrong, you will need this information to restore functionality:
- Pool configuration: Log into the miner’s web interface, navigate to the Miner Configuration page, and screenshot or copy your pool URLs, worker names, and passwords for all three pool slots
- Network settings: Note the miner’s IP address, subnet mask, gateway, and DNS settings — especially if you are using static IPs
- Current firmware version: Go to System Status and record the exact firmware version string (e.g., Antminer-S19-2024xxxx)
- Hashrate baseline: Record your current average hashrate and chip temperatures. After the update, you will compare against these numbers to verify the update was successful
- Fan speed settings: If you have custom fan speed configurations, note them
2. Check Model Compatibility
Firmware is not interchangeable between models. An S19 Pro firmware file will not work on an S19j Pro, even though they share the same BM1398 ASIC chip. An S21 firmware file will not work on a T21 in most cases. And critically — within the same model, different control board types require different firmware builds.
Before downloading any firmware file, verify:
- The firmware file name matches your exact model (S19, S19 Pro, S19j Pro, S19k Pro, S21, T21, etc.)
- The firmware is built for your specific control board type (Xilinx, BBB, Amlogic, or CV1835)
- For alternative firmware, check the supported models list on the developer’s website
3. Verify Firmware File Integrity
Corrupted firmware files are a leading cause of bricked miners. Always verify the integrity of your downloaded firmware before flashing:
Get-FileHash .\Antminer-S19-firmware.tar.gz -Algorithm SHA256
sha256sum Antminer-S19-firmware.tar.gz
Compare the output hash against the checksum listed on the download page. If they do not match, the file is corrupted — delete it and re-download from the official source. Never flash a firmware file whose checksum you have not verified.
4. Power Considerations
A power loss during a firmware write is the single most common cause of bricked miners. The control board’s NAND storage is being rewritten during the flash — if the process is interrupted mid-write, the bootloader, kernel, or filesystem can be left in a partially-written state that makes the miner unbootable. Before starting:
- Ensure your miner is on a stable power source — if you experience frequent power outages, use a UPS (uninterruptible power supply) for the miner during the update
- Ensure your network connection is stable — if uploading firmware via the web interface, a dropped connection during upload will corrupt the transfer
- Do NOT click any buttons, refresh the page, or close the browser during the flash process
- Do NOT power cycle the miner until it has fully rebooted and the web interface is accessible again
5. Firmware Download Sources
Only download firmware from trusted sources. Malicious firmware can redirect your hashrate to an attacker’s wallet — a real and documented attack vector in Bitcoin mining.
Trusted Firmware Sources
| Bitmain (Stock) | service.bitmain.com/support/download |
|---|---|
| D-Central (Stock Archive) | d-central.tech/downloads/firmwares |
| Braiins OS+ | braiins.com/os-firmware/download |
| VNish | vnish.com (official domain — beware imitations) |
| LuxOS | luxor.tech/firmware |
VNish in particular has multiple impersonation domains (vnish.us, vnish.net, vnish-firmware.com, vnish.farm, etc.) that may or may not be official. Always verify you are downloading from the developer’s legitimate domain. Malicious firmware that hijacks hashrate is a real and well-documented threat. When in doubt, download from D-Central’s Firmware Download Center.
Method 1: Web Interface Update (Stock Firmware)
The web interface method is the simplest and most common way to update Antminer firmware. It works for all models from the S9 through the S21 and requires nothing more than a web browser, a network connection to your miner, and the correct firmware file.
Step-by-Step Procedure
Step 1: Access the Miner’s Web Interface
Open a web browser and navigate to your miner’s IP address (e.g., http://192.168.1.100). Log in with your credentials. Default credentials for most Antminers are username root and password root. If you have changed these, use your custom credentials.
Step 2: Navigate to the Upgrade Page
In the web interface, go to System > Firmware Upgrade. On newer firmware versions (S19/S21), this may be under System > Upgrade. The page will show your current firmware version and provide an upload form.
Step 3: Upload the Firmware File
Click the Choose File or Browse button. Select the firmware .tar.gz file you downloaded earlier. Do NOT extract the archive — the miner expects the compressed .tar.gz file. Some models may also accept .img files depending on the firmware version.
Step 4: Flash the Firmware
Click Flash Image, Upgrade, or Upload (button text varies by firmware version). You may see a checkbox labeled “Keep settings” — check this if you want to preserve your pool configuration and network settings through the update. If you are experiencing issues and want a clean flash, leave it unchecked.
The upload and flash process takes 1–5 minutes depending on the firmware size and your network speed. During this time, do NOT close the browser tab, refresh the page, navigate away, or power cycle the miner. The page will typically display a progress indicator or a message asking you to wait.
Step 5: Wait for Automatic Reboot
After the firmware is written, the miner will automatically reboot. This takes 2–5 minutes. You may temporarily lose the web interface connection during reboot — this is normal. Wait for the miner’s LED to return to a steady green state.
Step 6: Verify the Update
Once the miner reboots, log back into the web interface. Navigate to System > System Status or the dashboard. Verify:
- The firmware version matches the version you just flashed
- All hashboards are detected (3 for S9/S17, 3-4 for S19, 3 for S21 — check your model’s spec)
- Hashrate is ramping up to expected levels (give it 10–15 minutes to stabilize)
- Chip temperatures are within normal range
- Pool connections are active (reconfigure if you did a clean flash)
Method 2: SD Card Flash (Recovery / Downgrade)
The SD card method is the recovery lifeline for bricked miners — and it is the only way to perform certain operations like firmware downgrades or reflashing a control board that will not boot far enough to serve its web interface. If the web interface is inaccessible and the miner is stuck in a boot loop or showing no network activity, SD card flashing is your path back.
SD Card Requirements
SD Card Specifications
| Capacity | 8 GB or smaller — Bitmain recommends <16 GB. Larger cards are unreliable for this purpose |
|---|---|
| Format | FAT32 — not exFAT, not NTFS. Windows may default to exFAT for cards >32 GB |
| Type | MicroSD (with adapter if needed for your card reader) |
| Speed Class | Class 10 or UHS-I recommended — not critical but avoids slow-read errors |
| Brand | Use reputable brands (SanDisk, Samsung, Kingston). Off-brand cards with fake capacity markings will cause failures |
SD Card Preparation
Step 1: Insert the MicroSD card into your computer using a card reader.
Step 2: Format the card as FAT32. On Windows, right-click the drive in File Explorer, select Format, choose FAT32, and check Quick Format. On macOS, use Disk Utility and format as MS-DOS (FAT). On Linux, use mkfs.vfat /dev/sdX.
Step 3: For S9, S17, and older models — download the SD card firmware package from Bitmain or D-Central. Extract the archive and copy ALL files to the root of the SD card (not inside a subfolder).
Step 4: For S19 and S21 models — download the SD card firmware image file (.img). Use balenaEtcher to write the .img file directly to the SD card. Do NOT simply copy the file — balenaEtcher writes the image at the block level, creating a bootable card.
SD Card Flashing by Antminer Generation
S9 Series (BM1387)
The S9 is the easiest miner to SD card flash. The MicroSD slot is located on the control board, accessible from the outside of the miner without disassembly.
- Power off the miner and unplug all cables
- Insert the prepared MicroSD card into the slot on the control board (next to the Ethernet port)
- Power on the miner
- Wait at least 90 seconds — the firmware will load automatically from the SD card
- The red and green LEDs will blink during the flash process
- When the LEDs stabilize (typically both blink then settle), the flash is complete
- Power off the miner, remove the SD card, then power on normally
S17 / T17 Series (BM1397)
The S17 and T17 series have an external MicroSD slot on the control board, similar to the S9. The flashing procedure is the same as the S9:
- Power off and unplug
- Insert prepared SD card into the slot (check for a small slot near the Ethernet port on the control board faceplate)
- Power on and wait 2–3 minutes
- Watch for LED activity indicating the flash is in progress
- Power off, remove SD card, power on to boot from NAND
The S17 and T17 series are notoriously sensitive to firmware versions. Certain firmware releases are known to cause hashboard detection failures, overheating issues, and chronic instability — particularly on units that have experienced frequent power outages at hydropower mining farms. If your S17/T17 is unstable after an update, try reverting to an older known-stable firmware version. D-Central maintains an archive of legacy firmware versions for exactly this purpose. When testing new firmware on S17/T17 units, Bitmain recommends starting with a small batch (10-30 units) and running for at least 24 hours before deploying to a full fleet.
S19 / T19 Series (BM1398)
The S19 series is where SD card flashing gets complicated, because the SD card slot location — and whether an SD card slot exists at all — depends on your control board type:
S19 SD Card Flashing by Control Board Type
| Control Board | SD Card Location | Procedure |
|---|---|---|
| Xilinx (Zynq) | External — next to Ethernet port | Same as S9/S17: insert card, power on, wait, remove card, reboot |
| BeagleBone Black | Internal — on underside of control board | Must open miner enclosure. Remove control board cover screws, locate SD slot on bottom of board, insert card, reassemble, power on |
| Amlogic | No SD card slot | Use Micro USB port with USB flash drive via OTG adapter. Write firmware image to USB drive using balenaEtcher, connect via OTG cable to Micro USB port on control board |
For BeagleBone Black control boards, the SD card must be accessed internally:
- Power off and fully unplug the miner
- Remove the screws holding the control board cover plate
- Carefully flip or lift the control board to access the MicroSD slot on its underside
- Insert the prepared MicroSD card (written with balenaEtcher for S19 firmware images)
- Reassemble the control board, reconnect all cables
- Power on and wait 3–5 minutes for the flash to complete
- Power off, disassemble again, remove the SD card, reassemble, power on
For Amlogic control boards (no SD slot):
- Prepare a USB flash drive (≤16 GB, FAT32)
- Use balenaEtcher to write the firmware .img file to the USB drive
- Connect the USB drive to the Amlogic control board’s Micro USB port using a USB OTG adapter/cable
- Power on the miner
- Monitor status LEDs — when the light turns static green, flashing is complete
- Power off, remove USB drive, power on normally
S21 / T21 Series (BM1370)
The S21 and T21 series predominantly ship with Amlogic control boards. The SD card recovery procedure follows the Amlogic USB method described above — use a USB flash drive with an OTG adapter connected to the Micro USB port on the control board.
Some early S21 units may have different control board variants. Check your specific board markings and refer to the S19 control board identification table above. The Bitmain support site provides model-specific SD card firmware downloads for the S21 series.
Method 3: Braiins OS+ Installation
Braiins OS+ is our recommended alternative firmware for miners who prioritize efficiency, transparency, and decentralization. For a complete walkthrough, see our Braiins OS+ setup guide. Its per-chip autotuning alone can improve your joules-per-terahash by 10-20% compared to stock firmware. Add Stratum V2 support — the only firmware that offers it — and you have a platform that aligns perfectly with the Bitcoin Mining Hacker ethos: maximum sovereignty, maximum efficiency, minimum waste.
Why Braiins OS+
- Per-chip autotuning: Analyzes every individual ASIC chip and adjusts its frequency based on quality. Higher-quality silicon runs faster, lower-quality silicon runs slower — the net result is better efficiency across the board
- Power target mode: Set a watt target (e.g., 2000W) and Braiins OS+ automatically tunes all chips to hit that power draw while maximizing hashrate within that budget
- Stratum V2: Authenticated encryption prevents hashrate hijacking. Transaction selection by the miner, not the pool. This is what mining decentralization actually looks like in practice
- Open-source: The code is public. No black boxes, no hidden devfees beyond what is disclosed
- Batch management: BOS Toolbox can install, update, configure, and monitor hundreds of miners simultaneously
Supported Models
Braiins OS+ Supported Antminer Models
| Generation | Supported Models | Control Boards |
|---|---|---|
| S9 Series | S9, S9i, S9j | Standard S9 control board |
| S17 Series | S17, S17 Pro, S17+, S17e, T17, T17+, T17e | Xilinx |
| S19 Series | S19, S19 Pro, S19j, S19j Pro, S19j Pro+, S19k Pro, S19 XP, S19j XP, S19e XP, T19, and Hydro variants | Xilinx (Zynq), BBB, Amlogic, CV1835 |
| S21 Series | S21, S21+, S21 Pro, S21 XP, S21 Hydro, S21 Immersion, S21 XP Hydro, S21 XP Immersion, S21+ Hydro, T21 | Amlogic |
Installation via BOS Toolbox (Recommended)
BOS Toolbox is Braiins’ management utility that handles installation, updates, configuration, and batch operations. It is available for Windows, macOS, and Linux.
Step 1: Download BOS Toolbox
Download the latest version from braiins.com/toolbox. Extract the archive to a folder on your computer.
Step 2: Prepare Your Miner List
Create a text file named miners.csv in the same directory as the Toolbox executable. Add one miner IP address per line:
192.168.1.100 192.168.1.101 192.168.1.102
Step 3: Run the Installation
bos-toolbox.exe install miners.csv
./bos-toolbox install miners.csv
The Toolbox will SSH into each miner (default credentials root:root), back up the original firmware, and install Braiins OS+. This process takes 5–10 minutes per miner. During the enhanced installation, you can configure your pool, power target, and cooling settings upfront so the miner starts mining immediately after installation.
Step 4: Verify Installation
After installation, access the miner’s web interface. The Braiins OS+ dashboard will replace the stock Bitmain interface. Navigate to Mining > Performance to select an autotuning profile. The miner will restart itself several times over the next few hours as it tunes each chip individually.
Installation via SSH (Manual)
If BOS Toolbox is not an option, you can install Braiins OS+ manually via SSH:
- Download the Braiins OS+ installation package for your specific model from braiins.com
- SSH into your miner: ssh [email protected] (password: root or your custom password)
- Transfer the installation package to the miner using scp
- Execute the installation script as per the instructions included in the package
- The miner will reboot into Braiins OS+ automatically
Reverting to Stock Firmware
Braiins OS+ includes a built-in uninstall mechanism. To revert to stock Bitmain firmware:
bos-toolbox.exe uninstall miners.csv
This restores the original Bitmain firmware that was backed up during installation. If the backup is corrupted or unavailable, you can use the SD card method described in Method 2 to flash stock firmware manually.
Method 4: VNish Installation
VNish is the firmware for miners who want maximum control. Our dedicated VNish firmware guide covers every detail of installation and tuning. Where Braiins focuses on efficiency and protocol innovation, VNish focuses on raw tunability — overclocking profiles, preset switching, chip-level throttling, and hardware-pushing performance modes. The 2.8% DevFee is straightforward: no subscriptions, no hidden fees, all features unlocked, free updates forever.
Key Features
- Overclocking profiles: Push hashrate up to +30% above stock (hardware and cooling dependent)
- Preset Switcher: Automatically switch between performance profiles based on temperature, fan speed, or manual schedule
- Chip Throttling: Available for S21 series — throttle individual underperforming chips instead of shutting down the entire hashboard
- Enhanced security: Built-in brute-force protection for miner passwords
- Scrypt support: One of the few alternative firmware platforms supporting L7 and L9 Scrypt miners
- Wide model support: S9, S17/T17 series, S19/T19 series, S21/T21, L7, L9, and Hydro/Immersion variants
Supported Models
VNish Supported Antminer Models
| Generation | Supported Models |
|---|---|
| S9 Series | S9, S9i, S9j, S9k, S9 SE |
| S17 Series | S17, S17 Pro, S17+, S17e, T17, T17+, T17e |
| S19 Series | S19, S19 Pro, S19j, S19j Pro, S19j Pro+, S19k Pro, S19 XP, S19j XP, S19e XP, T19, T19 Pro, and Hydro variants |
| S21 Series | S21, S21+, S21 Pro, S21 XP, S21 Immersion, T21, and Hydro variants |
| Scrypt (L-Series) | L7, L9 |
Installation Methods
VNish offers two primary installation methods:
Method A: SD Card / USB Installation (All Users)
- Download the VNish firmware image for your specific model from the official VNish site
- For miners with SD card slots (S9, S17, Xilinx/BBB S19): prepare a MicroSD card following the SD Card Preparation steps above
- For Amlogic boards: prepare a USB flash drive and use an OTG adapter
- Insert the media, power on, wait for the flash to complete (LED turns solid green), power off, remove media, power on
Method B: Hashcore Toolkit (Large Operations)
- Download the Hashcore Toolkit from the VNish website
- The toolkit enables remote installation directly to NAND memory without physical access to the miner
- Point the toolkit at your miners’ IP addresses and initiate the flash
- This method installs firmware to NAND, meaning no SD card or USB drive needs to remain inserted
VNish can run from the SD card (SD mode) or be installed directly to the miner’s internal NAND storage (NAND mode). SD mode is simpler — insert the card and the miner boots from it. Remove the card and the miner reverts to whatever firmware was previously on NAND. NAND mode installs permanently (until you reflash with something else) and does not require the card to remain inserted. SD mode is great for testing; NAND mode is for production deployment.
Post-Installation Configuration
After VNish boots, access the miner’s web interface. The VNish dashboard will display with its own UI. Configure your pools, then navigate to the performance/tuning section to select a preset profile or configure custom chip frequencies. Start conservatively — run at stock settings for 24 hours to establish a baseline, then gradually adjust overclock or underclock profiles.
Method 5: LuxOS Installation
LuxOS is the security-first, enterprise-grade firmware from Luxor Technologies. See our complete LuxOS firmware guide for detailed setup instructions. It is the only ASIC firmware with SOC 2 Type 2 certification, which means an independent auditor has verified that LuxOS meets institutional standards for security, availability, processing integrity, and data privacy. For operations that need compliance documentation — or for home miners who simply want the most security-vetted firmware on the market — LuxOS is the answer.
Key Features
- Dynamic hashprice optimization: Automatically adjusts between efficiency mode and overclocking mode based on real-time hashprice conditions
- PSU Bypass Mode: Run select S19 models on standard 120V household power — a game-changer for home miners who cannot install 240V circuits
- Chip health checker: Monitors hash output per chip to identify underperforming silicon before it causes board-level issues
- Hashrate Split: Direct portions of your hashrate to different pools simultaneously
- SOC 2 Type 2: The only firmware with institutional-grade security certification
- Non-destructive installation: LuxOS runs from the SD card — remove the card and your miner reverts to its original firmware. No NAND modification required
Supported Models
LuxOS primarily supports the S19 and S21 series:
- Antminer S19, S19 Pro, S19j, S19j Pro, S19j Pro+, S19k Pro, S19 XP
- Antminer T19
- Antminer S21, S21 Pro, T21
- Select Hydro and Immersion variants
Check luxor.tech/firmware for the current compatibility list, as new models are added regularly.
Installation via LuxOS Commander
Step 1: Download LuxOS Commander from luxor.tech/firmware. LuxOS Commander is available for Windows, macOS, and Linux.
Step 2: Launch LuxOS Commander. The tool will scan your local network and detect any compatible Antminer devices.
Step 3: Select your miner(s) from the detected list. Choose the LuxOS firmware version to install.
Step 4: LuxOS Commander will handle the firmware installation. The process takes a few minutes and preserves your existing pool configuration.
Step 5: After installation, access the LuxOS web dashboard through your miner’s IP address. Configure power targets, cooling profiles, and pool settings.
SD Card Method
LuxOS can also be installed via SD card for a non-destructive deployment:
- Download the LuxOS SD card image for your model
- Write the image to a MicroSD card using balenaEtcher
- Insert the MicroSD card into the miner’s control board SD slot
- Power on — the miner will boot from the SD card running LuxOS
- The SD card must remain inserted for LuxOS to continue running
- To revert to stock firmware, simply power off, remove the SD card, and power on
This approach is ideal for testing LuxOS without committing — try it risk-free and revert in 30 seconds.
Model-Specific Firmware Notes
Every Antminer generation has its own firmware quirks, known issues, and best practices. This section covers generation-specific details that go beyond the general procedures above.
S9 Series (BM1387) — The Immortal Workhorse
S9 Firmware Quick Reference
| ASIC Chip | BM1387 — 16nm |
|---|---|
| Hashboards | 3 boards, 63 chips each (189 total) |
| Hashrate (stock) | ~13.5 TH/s |
| Control Board | Single type — external MicroSD slot |
| SD Card Flash | Straightforward — external slot, FAT32, copy files to root |
| Alt Firmware | Braiins OS+, VNish, numerous others (most widely supported model) |
The S9 is the most firmware-compatible Antminer ever made. It has a single control board type with a universally accessible MicroSD slot, and every major alternative firmware platform supports it. Braiins OS+ on the S9 enables underclocking to as low as ~7 TH/s at <500W, making it the ultimate Bitcoin Space Heater platform — dual-purpose heating and mining from a machine that costs less than a space heater at most used hardware dealers.
The S9’s biggest firmware consideration is its age. Bitmain has stopped releasing new stock firmware for the S9 series. The last official updates focused on stability and bug fixes. For continued support and feature development, alternative firmware is the way to go. Braiins OS+ continues active development for S9, ensuring it remains a viable mining platform.
S17 / T17 Series (BM1397) — Handle With Care
S17/T17 Firmware Quick Reference
| ASIC Chip | BM1397 — 7nm |
|---|---|
| Hashboards | 3 boards |
| Hashrate (stock) | S17: ~56 TH/s | S17 Pro: ~53 TH/s | S17+: ~73 TH/s | T17: ~40 TH/s |
| Control Board | Xilinx-based — external MicroSD slot |
| Known Issue | Firmware version sensitivity — bad versions cause hashboard failures |
| Alt Firmware | Braiins OS+, VNish (use with caution on unstable units) |
The S17 and T17 series have the worst firmware reputation in the Antminer family. These machines are sensitive to firmware versions in ways that no other generation is. Certain firmware releases have been linked to:
- Hashboard detection failures (one or more boards dropping off)
- Chronic overheating even in properly ventilated environments
- Power delivery instability leading to unexpected shutdowns
- Failures exacerbated by frequent power outages (common in hydropower mining operations)
If your S17/T17 is working stably on its current firmware, think twice before updating. The “if it ain’t broke, don’t fix it” principle applies more to this generation than any other. If you must update, test on a single unit for at least 24 hours before deploying to additional machines.
Alternative firmware can actually improve S17/T17 stability — Braiins OS+ and VNish both include optimized thermal management and frequency tuning that can smooth out the instability issues that plague these machines on stock firmware. Underclocking an unstable S17 to 80% of its rated hashrate via Braiins OS+ often produces a more reliable machine than running at stock settings.
S19 / T19 Series (BM1398) — Know Your Board
S19/T19 Firmware Quick Reference
| ASIC Chip | BM1398 — 7nm |
|---|---|
| Hashboards | 3 or 4 boards (model dependent) |
| Control Board Types | Multiple: Xilinx, BBB, Amlogic, CV1835 — firmware is NOT interchangeable |
| Critical Issue | Must match firmware to control board type |
| Amlogic Lock | Boards manufactured post-March 2024 may require unlocking for alt firmware |
| Alt Firmware | All three platforms: Braiins OS+, VNish, LuxOS |
The S19 series is the most firmware-complex Antminer generation because of its four different control board types. The single most important thing you can do before any firmware operation on an S19 is identify your control board. Flashing Xilinx firmware onto an Amlogic board — or vice versa — will brick the device.
The firmware architecture is fundamentally different between control board types. Xilinx boards have an FPGA component that handles real-time data streaming to and from ASIC chips. BBB and Amlogic boards handle this in software. The firmware binaries are completely incompatible between these architectures.
All three major alternative firmware platforms support the S19 series across all control board types, but you must download the correct build for your specific board. Braiins OS+, VNish, and LuxOS all provide separate downloads labeled by control board type.
S21 / T21 Series (BM1370) — The Latest Generation
S21/T21 Firmware Quick Reference
| ASIC Chip | BM1370 — 5nm |
|---|---|
| Hashboards | 3 boards |
| Hashrate (stock) | S21: ~200 TH/s | S21 Pro: ~234 TH/s | S21 XP: ~270 TH/s | T21: ~190 TH/s |
| Control Board | Predominantly Amlogic — no SD card slot, Micro USB only |
| Recovery | USB flash drive via OTG adapter to Micro USB port |
| Alt Firmware | Braiins OS+ (since v24.03), VNish, LuxOS |
The S21 is Bitmain’s current flagship and represents the cutting edge of ASIC mining technology. With 5nm BM1370 chips pushing 200+ TH/s, the S21 demands firmware that can fully exploit its capabilities.
Firmware updates on S21 units primarily happen through the web interface for stock firmware, or via the respective management tools (BOS Toolbox, Hashcore Toolkit, LuxOS Commander) for alternative firmware. SD card recovery uses a USB flash drive via the Micro USB port with an OTG adapter, since the Amlogic control board has no SD card slot.
VNish’s chip throttling feature is particularly valuable on S21 units — if an individual chip degrades, VNish can throttle that specific chip’s frequency rather than reducing the entire hashboard’s performance or taking it offline.
L3+ / L7 / L9 (Scrypt) — Algorithm-Specific Firmware
L-Series (Scrypt) Firmware Quick Reference
| L3+ ASIC Chip | BM1485 |
|---|---|
| L7 ASIC Chip | BM1416 |
| Algorithm | Scrypt (Litecoin, Dogecoin) |
| L3+ Hashboards | 4 boards, 72 chips each |
| Alt Firmware | VNish (L7, L9); limited options for L3+ |
Scrypt miners use algorithm-specific firmware — you cannot flash SHA-256 firmware onto an L-series miner. The L3+ is one of the most widely deployed mining platforms ever and has a straightforward firmware update process via the web interface or SD card (external slot, same as S9). The L7 and L9 are supported by VNish, making it the go-to alternative firmware for Scrypt mining operations.
The L3+ is commonly repurposed as a Bitcoin Space Heater platform, similar to the S9. While it mines Litecoin/Dogecoin instead of Bitcoin, the heat output and compact form factor make it an excellent dual-purpose device. Firmware updates on the L3+ follow the same web interface and SD card procedures as the S9.
Troubleshooting
Even when you follow every step perfectly, firmware operations can go sideways. This section covers the most common failure scenarios and their solutions. The vast majority of firmware issues are recoverable — a truly “dead” miner from a firmware flash is rare if you have access to the SD card (or USB) recovery method.
Firmware Update Fails Mid-Flash
Diagnosis: Update Failed During Web Interface Flash
| Symptom | Web interface displays error message during upload, progress bar stops, or browser shows connection timeout |
|---|---|
| Likely Causes | 1) Network interruption during upload 2) Corrupted firmware file 3) Insufficient storage on control board 4) Browser timeout |
| Recovery |
|
Miner Will Not Boot After Update
Diagnosis: Miner Stuck in Boot Loop or No Network
| Symptom | LEDs cycle endlessly (boot loop), or miner powers on but never appears on the network, or LEDs show solid red on boot — consult our Antminer error code reference for LED diagnostic meanings |
|---|---|
| Likely Causes | 1) Corrupted firmware write (power interrupted during flash) 2) Wrong firmware flashed for this model/control board 3) Incompatible firmware version |
| Recovery |
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Wrong Firmware Flashed
Diagnosis: Flashed Firmware for Wrong Model or Control Board
| Symptom | Miner does not boot, boots but shows no hashboards, or boots to a different model’s web interface with errors everywhere |
|---|---|
| Risk Level | High — flashing firmware for a different control board type (e.g., Xilinx firmware on an Amlogic board) can brick the device in ways that are difficult to recover without professional equipment |
| Recovery |
|
SD Card Not Detected
Diagnosis: Miner Ignores SD Card During Recovery
| Symptom | Miner boots to its existing (broken) firmware and ignores the SD card entirely. No LED activity indicating a flash in progress |
|---|---|
| Likely Causes | 1) SD card not formatted as FAT32 2) SD card too large (>16 GB) 3) Files placed in subfolder instead of root 4) SD card slot is dirty or damaged 5) Using wrong media type (SD on Amlogic — needs USB) |
| Recovery |
|
Hashboards Missing After Update
Diagnosis: Fewer Hashboards Detected After Firmware Update
| Symptom | Miner boots and mines, but one or more hashboards are not detected. Hashrate is lower than expected |
|---|---|
| Likely Causes | 1) Firmware version incompatibility with hashboard revision 2) Loose ribbon cable connection (may have been disturbed if miner was opened for SD card access) 3) Firmware configuration issue |
| Recovery |
|
Cannot Revert from Alternative Firmware
Diagnosis: Stuck on Alt Firmware, Cannot Return to Stock
| Symptom | Attempted to uninstall alternative firmware but stock firmware will not flash, or uninstall process fails |
|---|---|
| Recovery |
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Frequently Asked Questions
Can I brick my miner by updating firmware?
Yes, but it is almost always recoverable. The most common cause of a bricked miner is a power interruption during the flash process. If your miner will not boot after a firmware update, the SD card (or USB) recovery method can almost always bring it back. True hard bricks — where even SD card recovery fails — are rare and typically indicate a hardware problem (damaged NAND flash chip or corrupted bootloader). D-Central repairs bricked control boards regularly at our Laval facility — learn more about our ASIC repair services.
Does alternative firmware void my Bitmain warranty?
Technically, yes — Bitmain’s warranty terms specify that running third-party firmware voids the warranty. In practice, Bitmain warranties are short (typically 180 days), and most miners in the field are well past warranty. If your miner is still under warranty, consider whether the efficiency gains from alternative firmware outweigh the warranty protection. You can always revert to stock firmware before sending a unit to Bitmain for warranty service.
Is the DevFee on alternative firmware worth it?
For most miners, yes. Braiins OS+ and VNish typically improve efficiency by 10-25% compared to stock firmware. Even with a 2-3% DevFee, the net improvement in joules-per-terahash results in lower electricity costs and higher effective hashrate. Do the math for your specific electricity rate and hashrate — in most scenarios, the efficiency gains more than offset the DevFee. The DevFee is essentially a small percentage of the additional hashrate you would not have had on stock firmware.
Can I update firmware remotely without physical access to the miner?
Yes — for web interface updates and alternative firmware installations. The web interface method only requires network access to the miner’s IP address. BOS Toolbox, VNish Hashcore Toolkit, and LuxOS Commander all support remote installation over SSH. The only method that requires physical access is SD card / USB recovery, which is typically only needed when the miner is bricked and cannot be reached over the network.
How do I identify my control board type without opening the miner?
Check the miner’s web interface — the System Status page usually indicates the control board type or firmware build target. Alternatively, look at the external ports: if there is a MicroSD slot next to the Ethernet port, it is likely Xilinx. If there is a Micro USB port on the control board faceplate, it is Amlogic. If you see neither external slot, it is likely a BeagleBone Black board with an internal SD slot. You can also SSH into the miner and check cat /proc/cpuinfo — the processor identification will reveal the SoC type.
What happens if I flash S19 firmware onto an S21?
The miner will not function correctly and may not boot. The BM1398 (S19) and BM1370 (S21) are fundamentally different chips with different communication protocols, voltage requirements, and frequency ranges. The firmware will not be able to initialize the hashboards. Use SD card/USB recovery to flash the correct S21 firmware. There is no risk of permanent hardware damage from flashing the wrong model’s firmware — the issue is purely software-level — but you will need a recovery procedure to get back to a working state.
Should I update firmware on a miner that is running fine?
It depends. Security patches and bug fixes are generally worth installing. Performance updates are worth testing on a single unit first. For S17/T17 series specifically, do NOT update a stable miner unless you have a compelling reason — these machines are notoriously firmware-sensitive. For S19 and S21 series, updates are generally safe and often beneficial. Always back up your configuration before updating, and keep a copy of your current firmware version so you can revert if needed.
Can I switch between alternative firmware platforms (e.g., VNish to Braiins OS+)?
Yes. You can flash any supported firmware over any other firmware using the standard installation methods. To go from VNish (NAND mode) to Braiins OS+, simply run the BOS Toolbox installer — it will overwrite VNish on NAND with Braiins OS+. To go from Braiins OS+ to VNish, use the VNish Hashcore Toolkit or SD card method. If switching between platforms, it is generally cleanest to revert to stock firmware first, then install the new alternative firmware fresh.
How often should I update my miner’s firmware?
Check for updates quarterly. Critical security patches should be applied immediately. Feature updates can be evaluated at your discretion. Alternative firmware platforms (Braiins, VNish, LuxOS) release updates more frequently than Bitmain — subscribe to their announcement channels to stay informed. There is no need to update on every release; focus on updates that address issues you are experiencing or add features you want.
My miner’s web interface shows a different firmware version after the update than what I flashed. What happened?
This can happen if the update failed silently and the miner reverted to its previous firmware, or if you accidentally uploaded the wrong firmware file. Check the firmware file name against your model. Re-download the firmware, verify the SHA256 checksum, and try the update again. If the miner consistently shows the old version after attempted updates, the NAND write may be failing — try the SD card/USB method instead of the web interface.
Firmware Download Links & Resources
Firmware Download Sources
| Source | URL | Content |
|---|---|---|
| D-Central Firmware Center | d-central.tech/downloads/firmwares | Current stock firmware + legacy versions for all Antminer models |
| D-Central Legacy Firmware Archive | d-central.tech/downloads/old-firmwares | Older firmware versions for rollback and recovery |
| Bitmain Official | service.bitmain.com/support/download | Official stock firmware releases from Bitmain |
| Bitmain SD Card Guides | support.bitmain.com — SD Card Flashing | Official SD card recovery instructions per model |
| Braiins OS+ | braiins.com/os-firmware/download | Braiins OS+ firmware downloads and documentation |
| BOS Toolbox | braiins.com/toolbox | Braiins management and installation tool |
| VNish Firmware | vnish.com | VNish alternative firmware downloads |
| LuxOS Firmware | luxor.tech/firmware | LuxOS firmware downloads and LuxOS Commander |
| balenaEtcher | etcher.balena.io | Free tool for writing firmware images to SD cards and USB drives |
Additional Resources
| D-Central Control Board Guide | Identifying and replacing Antminer control boards |
|---|---|
| D-Central Error Code Reference | Complete Antminer error code and LED diagnostic guide |
| D-Central ASIC Repair Services | Professional repair for bricked, damaged, or malfunctioning miners |
| Braiins OS Documentation | Official Braiins OS+ documentation and setup guides |
| Braiins Control Board Blog | Detailed explanation of S19 control board variations |
Why D-Central
Firmware operations are where mining meets software engineering — and where things can go very wrong very fast if you do not know what you are doing. Since 2016, D-Central Technologies has been flashing, customizing, recovering, and troubleshooting Antminer firmware for thousands of miners. We are not a firmware developer — we are the people who install it, fix it when it breaks, and help miners choose the right firmware for their specific use case.
What we bring to the table:
- 2,500+ miners serviced at our Laval, Quebec facility — including hundreds of firmware recovery jobs on bricked machines
- Complete firmware archive — current and legacy stock firmware for every Antminer model, maintained for exactly those moments when you need a specific old version to recover a troubled machine
- Control board expertise — we stock replacement control boards (Xilinx, BBB, Amlogic) and can swap boards when firmware recovery is not possible
- Alternative firmware experience — we deploy and support Braiins OS+, VNish, and LuxOS across customer machines and can recommend the right platform for your needs
- Amlogic unlocking — for miners with locked control boards that block third-party firmware installation
- Canadian support — real humans in Quebec, available at 1-855-753-9997
Whether you need a single firmware flash, a fleet migration to Braiins OS+, recovery of a bricked S17, or advice on which alternative firmware fits your operation — D-Central is your partner. We do not just sell hardware. We keep it running.
Every hash counts.
D-Central Technologies — Bitcoin Mining Hackers since 2016.
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